Anthropomorphic test devices (ATDs), such as crash test dummies, are used as human surrogates to assess crash injuries. Several different systems and apparatuses have been introduced as an attempt to measure penetration, displacement, force, velocity, and acceleration on an ATD in the abdominal area. Although these systems and apparatuses have been somewhat successful in providing information related to one or more of the stated parameters, each of which have associated disadvantages and limitations.
One known apparatus for indicating ATD abdomen displacement resulting from belt loading is referred to as the “frangible abdomen”. The frangible abdomen is a dynamically tuned biofidelic insert. The insert is formed of a crushable Styrofoam®. The crush of the foam is used to determine the amount of “submarining” and to quantify the injury risk associated therewith. The term “submarining” refers to when a lap belt rises up over the pelvic bone of a vehicle occupant.
Although the frangible abdomen has been referred to as a biofidelic insert, it only provides some level of biofidelity. The term “biofidelic” refers to the biomechanical aspects of a device or the ability of a device to be loaded and to respond to such loading in a human like fashion. In general, a system that is biofidelic has similar static and dynamic characteristics as that of a human. The frangible abdomen is a one time or single use device that is formed of a load-sensitive foam. Since the frangible abdomen is completely formed of foam, it does not provide the other static and dynamic characteristics of a human abdomen, which is primarily filled with bodily fluids. For example, the frangible abdomen or portions thereof do not disperse, move, flex, react, or perform in response to collision interactions with objects as would a human abdomen. The objects, for example, may be a seat belt, a steering wheel, an air bag, or parts of an ATD, such as the ribs of a ribcage. Thus, the frangible abdomen is limited in its ability to provide information that can be used to assess the interactions therewith.
In addition, the frangible abdomen is not instrumented. In not being instrumented, the frangible abdomen is incapable of providing time-based information. As such, abdominal interaction and abdominal insert performance during a collision event cannot be determined.
There have been a number of systems to produce an instrumented abdominal region or an instrumented abdominal insert. Some of these systems have included string potentiometers, strain gauges, and telescoping rods. These systems have also been directed to belt interaction and have used deflection, force, fluid pressure, or contact switch signals to indicate an injury level. Although the systems have provided some indication of belt interaction or abdominal displacement, the systems do not provide or have minimal biofidelic and rate sensitive characteristics, and all of which have there own associated disadvantages or drawbacks.
There are several techniques that have been proposed to define an abdominal injury criteria for assessing injury risk. The most promising criterion is the viscous criterion. The viscous criterion refers to the value determined by multiplying the maximum velocity V(t) experienced by the normalized compression C(t) of an abdomen during a collision event. As such, it is desirable for an abdominal sensing system to provide velocity and/or compression information for a device over time.
Thus, there exists a need for an improved abdominal sensing system that is biofidelic that overcomes the above-stated disadvantages and limitations, and that provides the desired information needed for determining injury risk.